A related art method for manufacturing a CMOS image sensor may use a defocus phenomenon and a reflow phenomenon.
FIGS. 1 and 2 are drawings for describing a microlens of an image sensor of the related art.
FIG. 1 is a drawing showing an entire top image of a microlens, and FIG. 2 is a drawing showing the gap between microlenses. A microlens may be formed in a convex lens shape and may collect light to a photo diode.
FIGS. 3 and 4 are process cross-sectional drawings for describing a method for manufacturing a microlens of an image sensor of the related art.
Referring to FIG. 3, photo resist (PR) is applied on transparent underlayer 10 and the photo resist is exposed using mask 30. Photo resist pattern 20 may be formed in a trapezoid shape using a defocus phenomenon. Photo resist pattern 20 may also be heated to a melting point. A reflow phenomenon where photo resist pattern 20 may be rounded, having fluidity, may be then generated. In accordance with the defocus phenomenon and the reflow phenomenon, micro lens 21 in a shape as illustrated in FIG. 4 may be formed.
FIG. 5 is a drawing describing a stray beam passing the gap of microlenses of an image sensor of the related art.
Referring to FIG. 5, microlenses 21 formed using the defocus phenomenon and the reflow phenomenon may have various problems. For example, a gap may occur.
The image light of object 50 that may have entered through the gap between microlenses 21 may not be exactly focused on photo diode 40. The light that may have entered through the gap of microlenses 21 may go straight ahead and thus, it may be appreciated as stray beam which cannot be collected in photo diode 40 under transparent underlayer 10. Although the light transferred through microlens 21 may be focused on photo diode 40, other lights may become stray beam and may deteriorate image quality.